Your friend most certainly can not dismiss all arguments based on "what dad would want" . . . The law requires you to
"give effect, in so far as is practicable, to the past and present will and preferences of the relevant person, in so far as that will and those preferences are reasonably ascertainable..."
MOB is correct. In my earlier post I confused the duties of attorneys and the duties of trustees. My (pretty bad) mistake. Sorry!
Still, there is a difference between "the past and present will and preferences" of the donor of the power, and what the donor would want. The duty is to give effect to what the donor
did and does want, not what the donor
would want.
How can you tell what the donor wants, given that the donor is (usually) not in a position to say? Often the question arises in relation to an issue that was present all along, and on which the donor had a known position. So if the donor gave a monthly donation by standing order to the Vincent de Paul, for instance, you can continue that. It's also important to look at the terms of the document that grants the power of attorney; they may contain expressions of the donor's wishes, either in general or in relation to particular matters.
In a case like this, where one child has requested an advance on their inheritance, can we know the donor wants? Well, if the child previously requested an advance on their inheritance while the donor was still competent and was refused, we do know; the donor didn't want to do this. But, more likely, there was no previous request; this is a wholly new development. Given that the donor of the power is now demented, it's probably unlikely that they can give a reliable expression of what they want done about this; if so, we don't know what the donor wants. And the law also requires the attorney to
act at all times in good faith and for the benefit of the relevant person
So, if you don't and can't know what the donor does want, you don't speculate about what the donor would want and give effect to that; you act in the way that benefits the donor.